What is the first line of treatment for a typical patient experiencing a canker sore?

First-Line Treatment for Canker Sores

Start with topical corticosteroids as first-line therapy: betamethasone sodium phosphate 0.5 mg dissolved in 10 mL of water used as a 2-3 minute rinse-and-spit solution four times daily. 1, 2

Primary Treatment Protocol

Apply the following treatments immediately upon canker sore identification:

Topical Corticosteroid Options (choose one):

• Betamethasone sodium phosphate 0.5 mg in 10 mL water: Rinse for 2-3 minutes and spit, four times daily 1, 2
• Clobetasol propionate 0.05% ointment mixed 50% with Orabase: Apply twice weekly directly to dried mucosa for localized lesions on buccal mucosa or tongue 1, 2
• Fluticasone propionate nasules diluted in 10 mL water: Use twice daily as alternative 1, 2

These topical corticosteroids reduce inflammation and accelerate healing with minimal systemic side effects. 3

Pain Management (use concurrently)

Immediate pain relief measures:

• Benzydamine hydrochloride oral rinse: Apply every 3 hours, especially before eating 2, 4
• Viscous lidocaine 2%: Use 15 mL per application, up to 3-4 times daily for severe pain 2
• Gelclair mucoprotectant gel: Apply three times daily to form protective barrier over ulcerated surfaces 2

For children, use benzydamine hydrochloride every 2-4 hours and apply 2.5% lidocaine ointment sparingly only for severe pain interfering with eating. 4

Essential Supportive Care

Protective and cleansing measures:

• White soft paraffin ointment to lips: Apply every 2 hours throughout acute phase 5, 4
• Warm saline mouthwashes: Clean mouth daily to reduce bacterial colonization 2, 4
• Chlorhexidine digluconate 0.2% mouthwash: Use 10 mL twice daily as antiseptic rinse (dilute by 50% if causes soreness) 5, 2

Dietary modifications:

• Avoid crunchy, spicy, acidic foods and hot beverages during healing 2

When First-Line Treatment Fails

Escalate to second-line therapy if no improvement after 1-2 weeks:

• Tacrolimus 0.1% ointment: Apply twice daily for 4 weeks for recalcitrant lesions 1, 2
• Intralesional triamcinolone 28 mg weekly plus topical clobetasol for non-healing ulcers 1, 2

Reserve systemic corticosteroids for severe/recurrent cases:

• Oral prednisone/prednisolone 30-60 mg or 1 mg/kg daily for 1 week, then taper over second week 1, 2
• Use only when topical therapy fails and quality of life is significantly impacted 2

Critical Pitfalls to Avoid

Screen for secondary infections before assuming treatment failure:

• Candidal infection presents as white patches or persistent ulcers—treat immediately with nystatin oral suspension 100,000 units four times daily for 1 week or miconazole oral gel 5-10 mL four times daily 1, 2
• HSV reactivation may cause slow healing—consider antiviral therapy 5

Investigate further if ulcers persist beyond 3 weeks despite appropriate treatment:

• Obtain complete blood count to rule out leukemia or anemia 2
• Check fasting blood glucose (hyperglycemia predisposes to fungal infections) 2
• Consider HIV and syphilis serology if risk factors present 2
• Perform biopsy if multiple morphologically different ulcers or systemic symptoms present 2

Avoid these common errors:

• Do not use alcohol-containing mouthwashes—they exacerbate pain and delay healing 4
• Do not use combination antifungal/corticosteroid preparations for simple canker sores in children 4
• Do not delay topical corticosteroid initiation—early treatment provides better outcomes 1